To photograph an object with a low illuminance or an object illuminated with back light, an image sensing apparatus must use an electronic flash device.
White balance is adjusted in accordance with the color temperature of an object. In photographing an object using an electronic flash device, white balance must be determined in consideration of both the color temperature of the object and that of the electronic flash. As a method of determining white balance, a white balance control value is calculated on the basis of the illuminance of an object and the degree of influence of the light emission amount of an electronic flash device.
However, as can be understood from the graph in FIG. 6 which shows the white balance control characteristic for R and B signals, if a white balance control value to be actually controlled is simply calculated on the basis of the illuminance of an object and the degree of influence of the light emission amount of an electronic flash device in accordance with the ratio of the white balance control value for the color temperature of the object before illumination to the white balance control value for a color temperature based on the light emission amount of the electronic flash device, the calculated white balance control value deviates from a black body radiation characteristic indicated by the bold line.
As a result, if white balance is adjusted on the basis of the thus calculated white balance control value, the image exhibits color appearance little to magenta.